Electrochemiluminescent and luminescent nanoparticles for bioanalytical applications

In this PhD thesis, we prepared spherical and monodispersed silica nanoparticles of different sizes, doped with Ru(bpy)32+ and the neutral [Ru(bpy)2(bps)] heteroleptic complexes, containing carboxyl, or amino and phosphonate groups at their periphery. Their size was varied acting on the water-to-surfactant molar ratio of the microemulsion, obtaining samples between ~ 20 and ~140 nm. These systems showed ФPL and τ values higher than the reference dyes in aerated conditions. We proved that the ECL signal intensity depends on the size of the NPs with the highest ECL intensity obtained for the smallest NPs, showing a stronger interaction between the dyes and the coreactant. Moreover, DDSNPs doped with the [Ru(bpy)2(bps)], showed an ECL intensity higher than the one of the DDSNPs doped with Ru(bpy)32+. Photophysical evidence showed that the neutral complex [Ru(bpy)2(bps)] is mainly self-organized at the periphery of the particles, which favors the interaction with the TPrA coreactant. Ru(bpy)32+ was also used together with a water-soluble pyrene derivative to prepare in luminescent DDSNPs with a long-lived excited state. This approach was based on the Ru(bpy)32+/Py triplets interaction energy reservoir mechanism. With our strategy, we achieved for the DDSNPs a more than 5-fold elongation of the excited lifetime of Ru(bpy)32+ compared to the complex in aerated solution. A family of ECL active DDSNPs doped with Ru(bpy)32+ were also endowed with a polyamine-rich shell to develop self-enhancing ECL nanoarchitectures able to emit in the absence of coreactant in solution. This is a promising approach to increase the electronic interactions between dyes and coreactant, to exclude toxic TPrA, and to simplify the detection protocol, offering the possibility of ECL investigations on living cells. Finally, were prepared carbon quantum dots that were used to modify screen-printed carbon electrodes. The performances of these modified SPCEs to detect Troponin I, were evaluated and gave promising results.